The heart of the matter

The ongoing threat of acute coronary syndrome begins with a nasty process called atherosclerosisA study at the University of Alabama, Birmingham, indicates that a third of those over 65 who are having a heart attack do not experience chest pain.

Angina, the chest pain associated with heart disease, comes as a huge shock to someone who’s taken relatively good health for granted. “How can this be happening to me? I’ve never had heart trouble! Am I going to die?”

But chest pain is the heart’s way of saying, “Houston, we have a problem.” The heart’s muscular tissue, the myocardium, needs a constant supply of oxygen-rich blood, which can be diminished or even blocked by a chronic disease called atherosclerosis. (Derived from Greek, athero means gruel, sclerosis means hard.) The word describes the porridge-like appearance of areas within the arteries known as plaques. A family history of the disease, elevated cholesterol, smoking, high blood pressure, diabetes, obesity or lack of exercise can bring on the disease.

In fact, atherosclerosis can lead to problems in any of the arteries throughout the body. Most people have some plaque, says Dr. Cam Joyner, directoof the Non-invasive Laboratory, Division of Cardiology at Toronto’s Sunnybrook and Women’s College Health Sciences Centre. “It’s there but it’s not causing anything serious, other than the person may have some stable angina. [According to the American Medical Association, stable angina is chest pain brought on by exertion or stress. It usually lasts less than five minutes and is eased by rest.] Trouble arises when a superimposed blood clot forms [on a plaque]. If it occurs in the heart, then we’re dealing with acute coronary syndrome (ACS). If it occurs in the brain, it causes a stroke. And if it happens in the legs, it can cause similar problems there.” (Reduction in blood flow to a limb causes cramping, pain or weakness that is often worsened with exercise. In severe cases amputation may be necessary.)

The disease begins early
Atherosclerosis doesn’t happen overnight. It begins without symptoms, sometimes in childhood, when flat, yellowish, fatty streaks begin forming within large- and medium-sized artery walls. Over the years, many of these deposits progress to fibrous plaques that have a fatty filling mostly comprised of cholesterol. As plaques enlarge, they narrow the artery, reducing the amount of blood that can be delivered to tissues downstream.

The situation becomes dangerous when a plaque ruptures, spewing its contents into the blood and triggering a complex process of blood clot formation. Platelets, the small cells normally present in the blood, play a vital role, rushing to the injured plaque where they clump, initiating a clot or thrombus. This blood clot is the body’s way of trying to repair the ruptured plaque but the clot further impedes or even completely blocks blood flow.

Patients with a clot in an artery in their heart appear at emergency rooms complaining of chest pain lasting more than 20 minutes, often behind the sternum (breastbone), in the central chest and sometimes radiating up into the neck or arms. “The first thing that’s done is an electrocardiogram (ECG) to see if they have changes on the ECG that would suggest a lack of blood flow to the heart. That indicates acute coronary syndrome,” says Dr. Cam Joyner. “Within that acute coronary syndrome, there are basically two types of patients. One is called non-ST-elevation MI (the most common heart attack) and the other unstable angina. The differentiation, made by the attending doctor, is based on the electrocardiogram and the blood tests.” (MI, or myocardial infarction, means that heart tissue has died or been damaged by a blocked blood supply. Unstable angina is chest pain that has changed in nature over a period of time, occurs during rest or is happening for the first time.)

An urgent situation arises when the ECG points to a severe heart attack, with total occlusion or blockage in the artery. (The ECG shows an ST-segment elevation.) “Those patients are treated differently,” notes Joyner, “with clot-dissolving medications as opposed to blood thinners.”

Or they could be sent to an angiogram lab, where a tube is put into the heart to inject X-ray dye into the arteries to locate the blockage. A stent is a short metal mesh tube that can be placed in the affected site in the artery by balloon catheter, expanded and left there to keep the artery open. “In some cases,” says Joyner, “the patients will need bypass surgery.”

Fortunately, a new drug, Plavix (clopidogrel), along with Aspirin, is reducing incidence of a subsequent thrombus-induced event. Plavix inhibits the platelets tendency to clump together, providing the base for a clot.

Since clot formation plays a significant role in acute coronary syndrome, treatment aimed at managing clotting is vital. But the need to balance clot formation must be weighed against the body’s blood coagulation mechanism, essential in preventing life-threatening bleeding if an injury occurs.

Life-stretching drug therapy
Joyner points out that the ACS patient receives a cocktail of drugs to manage the condition, along with medication to prevent subsequent formation of clots. A beta-blocker reduces heart rate, blood pressure and lightens the heart’s workload. “Sometimes, nitroglycerine tablets or spray or long-lasting nitrates are given,” he says. “Another class of medication called ACE inhibitors has been shown to be beneficial. There’s a statin drug as well, to lower cholesterol.

“Once you’ve got this disease, you’ve probably got it throughout your arteries to a minor degree,” says Joyner. He believes drugs such as Aspirin and/or Plavix (clopidogrel) have a widespread and beneficial effect. “They thin the blood everywhere,” he says. “If you do angioplasty and put a stent in, it’s only going to deal with that local problem, not with the diffuse process involving all the other arteries in the body.” (Angioplasty is a technique used to widen narrowed coronary arteries.)

Important studies
Ironically, using balloon angioplasty or placing a stent in a blood vessel, even with Aspirin therapy, runs the risk of creating a clot at the site or launching tiny embolisms into the coronary circulation. In a study of nearly 2,700 ACS patients who received stents, half were treated with Plavix and Aspirin for at least six days prior to the procedure and for a year afterward. The others received Aspirin and a placebo (an inactive substance). Cardiovascular death or heart attack was reduced by nearly a third in the group treated with Plavix and Aspirin, compared with those given Aspirin and a placebo.

This study was part of a large clinical trial called CURE (Clopidogrel in Unstable Angina to Prevent Recurrent Ischemic Events), involving 12,562 patients with ACS. Again, patients treated early with Plavix and Aspirin who received the drugs on a long-term basis, fared better than those on placebo and Aspirin. In fact, the risk of heart attack, stroke and cardiovascular death in the Plavix- and Aspirin-treated group dropped by 20 per cent.

“The CURE study has caused a major change in how we treat patients with ACS,” says Joyner. He reports they are almost routinely being put on the combination of Plavix and Aspirin. He cautions that patients taking Plavix wouldn’t notice a difference in how they feel. “It doesn’t reduce angina. It doesn’t change shortness of breath,” he says. “But we know it prevents new heart attacks.”

The same goes for the other classes of drugs patients are given after ACS to try to reduce events. “Patients are quite keen to take whatever they have to take to feel better and do better,” he notes. “The down side is the number of pills that patients have to take in order to optimize their outcomes Ð and the cost.”

For patients over 65, certain drugs may be covered by their province’s drug plan. In Ontario, Plavix is not covered. Doctors can apply for coverage to the Ontario Drug Benefit Program (ODB) on a patient’s behalf by submitting a request for reimbursement called a Section 8. But a delay in approval for coverage for Plavix through the Section 8 process can potentially place patients at risk since they are not initiating therapy as prescribed by their doctor. As the cure trial demonstrated, drug therapy in the early days following ACS is critical to ensure maximum benefit.

Risk factors for acute coronary syndrome:
Unchangeable:

• Age: 45-plus males, 55-plus females.
• Family history of heart disease.
• Race: First Nations and Inuit Canadians have higher rates of heart disease.

Modifiable:

• Smoking or ongoing exposure to second-hand smoke.
• High blood pressure.
• High cholesterol levels, with high LDL (the “bad” cholesterol).
• Poorly controlled diabetes.
• Overweight (body mass index of 26 or 27) or obese (BMI over 27).
• Lack of exercise.
• Excessive stress.

Warning signs of a heart attack

• Pain, discomfort, pressure, or tightness in the chest.
• Pain in shoulders, arms, neck, back or jaw*.
• Discomfort similar to indigestion.
• Shortness of breath*.
• Sweating, nausea*.
• Faintness, dizziness.
• Weakness, anxiety.
• *More common in women

Minutes count.
If you suspect you may be having a heart attack, call 911 and get medical care as soon as possible.

This Special Sponsored Feature was produced by the editors of CARPNews FiftyPlus in co-operation with Bristol-Myers Squibb and Sanofi-Synthelabo Canada Inc.